1. Field of the Invention
This invention relates generally to the control of a transmission input clutch during a tip-in event using active damping that monitors input shaft speed of a dual clutch automatic transmission.
2. Description of the Prior Art
During normal operation of a dual-clutch automatic transmission the driven input is connected to the transmission output shaft through gears. Dual-clutch automatic transmission is sometimes referred to as powershift transmissions.
Powershift transmissions are sensitive to gear rattle in tip-in situations because of the lack of a torque converter as a damping device. It is possible for driveline oscillations to cause an audible sound in such transmissions during tip-in events due to oscillations in driveline torque and input speed causing speed and torque reversals on the transmission components.
The magnitude of torque that is transmitted by each of the input clutches, sometimes called input clutch torque capacity, must be carefully controlled to achieve an acceptable tip-in. If the clutch torque is increased too rapidly during a tip-in then the input shaft speed will start to oscillate, possibly causing gear rattle. But if the clutch torque is increased too slowly, the performance metrics for a tip-in will not be met, which can lead to driver dissatisfaction.